Messages in this thread | | | Date | Thu, 22 Aug 2019 09:40:11 -0700 | From | Greg KH <> | Subject | Re: [PATCH v5 1/2] usbip: Skip DMA mapping and unmapping for urb at vhci |
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On Fri, Aug 09, 2019 at 12:54:34AM +0900, Suwan Kim wrote: > vhci doesn’t do DMA for remote device. Actually, the real DMA > operation is done by network card driver. vhci just passes virtual > address of the buffer to the network stack, so vhci doesn’t use and > need dma address of the buffer of the URB. > > But HCD provides DMA mapping and unmapping function by default. > Moreover, it causes unnecessary DMA mapping and unmapping which > will be done again at the NIC driver and it wastes CPU cycles. > So, implement map_urb_for_dma and unmap_urb_for_dma function for > vhci in order to skip the DMA mapping and unmapping procedure. > > When it comes to supporting SG for vhci, it is useful to use native > SG list (urb->num_sgs) instead of mapped SG list because DMA mapping > fnuction can adjust the number of SG list (urb->num_mapped_sgs). > And vhci_map_urb_for_dma() prevents isoc pipe from using SG as > hcd_map_urb_for_dma() does. > > Signed-off-by: Suwan Kim <suwan.kim027@gmail.com>
Can you please redo this patch based on my usb-next branch that has Christoph's DMA changes in it? It should make your change much simpler and smaller.
Please do that and resend the whole series.
thanks,
greg k-h
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